Dear Anurag

Permitting change of branch within the college during 2nd year is decided  by the college authorities. Based on the number of applicants and their performance in 1st year of study , HoD is  seen to allot the vacant seats. This needs to be approved by the principal and later should be informed to administrative department as the USN needs to be changed.

Based on your rank i am sorry to say this but you won't be able to get computer science college's in elite comedk college's like RV, MSRIT etc. You can easily get following college's.

NIE institute of technology

Siddaganga institue of technology

Nitte Meenakshi institute of technology

BNM institute of technology

The closing rank of these college's is predicted to be around 8k - 12k.

Good luck.